On Sun, 2 Apr 2006 21:12:18 -0400
Bulent Aliev <atlasyts@bellsouth.net> wrote:

I have been trying to figure out why I'm having such a hard time
tuning the engine. The other day we ran the plane on the long taxiway
and it did not sound stable. We had occasional pops and the mixture
kept going too rich or too lean.
Today I was thinking if it has something to do with the fuel pressure
regulator being controlled by the manifold pressure. As the MP
varies, the FPR changes the fuel pressure. So the computer is trying
to compensate the injector output for manifold pressure, but the fuel
pressure is changing at the same time. I have seen the FP changing
from 35 psi at low RPM to 50 psi at high boost?
I wander if I should set the FPR at one value and let the EC2 take
care of the rest?

Buly
Resealing the oil pan/engine mount to cure oil leak
Welding a tiny leak in the radiator

Hi Buly,

I wonder if you have instability in your MP readings.  If the MP seen
by the EC2 and the fuel pressure regulator is unstable because of
pressure waves in the plenum (or whatever) you could see erratic changes
in the mixture. Do you have a restriction in the line to the MP port on
your intake? If not, you might try adding one.  Or, can you put the tap
for the MP in a different location?

Bob W.